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Groups > linux.kernel > #1628329
| From | Boris Ostrovsky <boris.ostrovsky@oracle.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave |
| Date | 2017-04-21 16:30 +0200 |
| Message-ID | <tyHJn-6SD-5@gated-at.bofh.it> (permalink) |
| References | <txuXT-2Q2-3@gated-at.bofh.it> <txuXU-2Q2-21@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
> +static bool __init xen_check_xsave(void)
> {
> - unsigned int ax, bx, cx, dx;
> - unsigned int xsave_mask;
> + unsigned int err, eax, edx;
>
> - ax = 1;
> - cx = 0;
> - cpuid(1, &ax, &bx, &cx, &dx);
> + /* Test OSXSAVE capability via xgetbv instruction. */
> + asm volatile("1: .byte 0x0f,0x01,0xd0\n\t" /* xgetbv */
> + "xor %[err], %[err]\n"
> + "2:\n\t"
> + ".pushsection .fixup,\"ax\"\n\t"
> + "3: movl $1,%[err]\n\t"
> + "jmp 2b\n\t"
> + ".popsection\n\t"
> + _ASM_EXTABLE(1b, 3b)
> + : [err] "=r" (err), "=a" (eax), "=d" (edx)
> + : "c" (0));
Have you tested this on processors where we actually trap on xgetbv?
I have an AMD box without XSAVE support and this is a fatal error. I
suspect it's too early to use exception fixup framework here.
-boris
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[PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Juergen Gross <jgross@suse.com> - 2017-04-18 08:40 +0200
Re: [Xen-devel] [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Andrew Cooper <andrew.cooper3@citrix.com> - 2017-04-18 12:10 +0200
Re: [Xen-devel] [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Juergen Gross <jgross@suse.com> - 2017-04-18 14:00 +0200
Re: [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-04-21 16:30 +0200
Re: [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Juergen Gross <jgross@suse.com> - 2017-04-21 16:40 +0200
Re: [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Andrew Cooper <andrew.cooper3@citrix.com> - 2017-04-21 20:30 +0200
Re: [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-04-21 21:30 +0200
Re: [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Juergen Gross <jgross@suse.com> - 2017-04-24 08:30 +0200
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